when do you implantation bleeding? Could this be it?

I am not suppose to start my period for three more days and never get it early. super rare if I do. Just went to the bathroom and I had a tiny bit of bright red blood on the toilet paper. My period always starts brown and gradually gets to red. Checked everything else and it does not appear I have started my period. hmmmm...... really hoping its not. Weirdest thing.